Isolation and characterization of three rat adult type beta-globin genes

Abstract

In order to clarify the molecular basis of the heterogeneity of rat hemoglobins, two DNA clones containing the genes for adult type beta-globins were isolated from a rat genomic DNA library. The results obtained in the present experiments are summarized as follows. 1) Clone lambda Rg beta 59 contained the gene for an adult rat beta-major globin, II beta, while clone lambda Rg beta 45 contained the genes for two adult rat beta-minor globins, III beta, and O beta, respectively. 2) The entire nucleotide sequences of these genes were determined, indicating that the genes are all composed of 3 exons and 2 introns, and code for 146 amino acid residues. The genes exhibited structural features typical to known expressed beta-like globin genes, implying that they are all functional. 3) The predicted amino acid sequences completely agreed with the amino acid sequences of II beta, III beta and O beta globins, respectively, which we isolated in a separate experiment. 4) Sequence comparisons of three rat globin genes with one another and with the known mouse beta-major and beta-minor globin genes showed the occurrence of interesting homologies between two species from evolutional aspects. 5) Southern hybridization analysis of the genomic DNA implies that a number of beta-like globin genes other than the present ones exist in the rat genome.